1. Field of the Invention
The present invention relates generally to the fabrication of semiconductor wafers, and, more particularly, to high density plasma etching chambers having internal surfaces that reduce particle and metallic contamination during processing.
2. Description of the Related Art
In the field of semiconductor processing, vacuum processing chambers are generally used for etching and chemical vapor depositing (CVD) of materials on substrates by supplying an etching or deposition gas to the vacuum chamber and application of an RF field to the gas to energize the gas into a plasma state. Examples of parallel plate, transformer coupled plasma (TCP(trademark)) which is also called inductively coupled plasma (ICP), and electron-cyclotron resonance (ECR) reactors and components thereof are disclosed in commonly owned U.S. Pat. Nos. 4,340,462; 4,948,458; 5,200,232 and 5,820,723. Because of the corrosive nature of the plasma environment in such reactors and the requirement for minimizing particle and/or heavy metal contamination, it is highly desirable for the components of such equipment to exhibit high corrosion resistance.
During processing of semiconductor substrates, the substrates are typically held in place within the vacuum chamber by substrate holders such as mechanical clamps and electrostatic clamps (ESC). Examples of such clamping systems and components thereof can be found in commonly owned U.S. Pat. Nos. 5,262,029 and 5,838,529. Process gas can be supplied to the chamber in various ways such as by a gas distribution plate. An example of a temperature controlled gas distribution plate for an inductively coupled plasma reactor and components thereof can be found in commonly owned U.S. Pat. No. 5,863,376. In addition to the plasma chamber equipment, other equipment used in processing semiconductor substrates include transport mechanisms, gas supply systems, liners, lift mechanisms, load locks, door mechanisms, robotic arms, fasteners, and the like. Various components of such equipment are subject to corrosive conditions associated with semiconductor processing. Further, in view of the high purity requirements for processing semiconductor substrates such as silicon wafers and dielectric materials such as the glass substrates used for flat panel displays, components having improved corrosion resistance are highly desirable in such environments.
Aluminum and aluminum alloys are typically used for walls, electrodes, substrate supports, fasteners and other components of plasma reactors. In order to prevent corrosion of the such metal components, various techniques have been proposed for coating the aluminum surface with various coatings. For instance, U.S. Pat. No. 5,641,375 discloses that aluminum chamber walls have been anodized to reduce plasma erosion and wear of the walls. The ""375 patent states that eventually the anodized layer is sputtered or etched off and the chamber must be replaced. U.S. Pat. No. 5,895,586 discloses that a technique for forming a corrosion resistant film of Al2O3, AlC, TiN, TiC, AlN or the like on aluminum material can be found in Japanese Application Laid-Open No. 62-103379. U.S. Pat. No. 5,680,013 states that a technique for flame spraying Al2O3 on metal surfaces of an etching chamber is disclosed in U.S. Pat. No. 4,491,496. The ""013 patent states that the differences in thermal expansion coefficients between aluminum and ceramic coatings such as aluminum oxide leads to cracking of the coatings due to thermal cycling and eventual failure of the coatings in corrosive environments. U.S. Pat. No. 5,879,523 discloses a sputtering chamber wherein a thermally sprayed coating of Al2O3 is applied to a metal such as stainless steel or aluminum with an optional NiAlx bond coating therebetween. U.S. Pat. No. 5,522,932 discloses a rhodium coating for metal components of an apparatus used for plasma processing of substrates with an optional nickel coating therebetween.
Materials for chamber walls, liners, rings and other parts of plasma chambers have also been proposed. See, for example, U.S. Pat. Nos. 5,366,585; 5,788,799; 5,798,016; 5,851,299 and 5,885,356.
As integrated circuit devices continue to shrink in both their physical size and their operating voltages, their associated manufacturing yields become more susceptible to particle and metallic impurity contamination. Consequently, fabricating integrated circuit devices having smaller physical sizes requires that the level of particulate and metal contamination be less than previously considered to be acceptable.
In view of the foregoing, there is a need for high density plasma processing chambers having internal, plasma exposed surfaces that are more resistant to erosion and assist in minimizing contamination (e.g., particles and metallic impurities) of the wafer surfaces being processed.
In a first embodiment of the present invention, a process of making a component of semiconductor processing equipment is provided. The process includes providing a cerium oxide containing ceramic layer on a surface of the component such that the cerium oxide containing ceramic layer forms an outermost surface of the component. The cerium oxide containing ceramic layer comprises one or more cerium oxides as the single largest constituent thereof.
In a second embodiment of the invention, a process of making a component of semiconductor processing equipment from a cerium oxide containing ceramic material is provided. The process includes steps of: preparing a slurry comprising cerium oxide; forming a green compact from the slurry in the desired shape; and sintering the green compact to form a cerium oxide containing ceramic component. The cerium oxide containing ceramic component comprises one or more cerium oxides as the single largest constituent thereof.
In a third embodiment of the present invention, a component of semiconductor processing equipment is provided wherein the component includes a cerium oxide containing ceramic material forming an outermost surface of the component. A plasma chamber including at least one component as set forth above is also provided.
In a fourth embodiment of the present invention, a method of processing a semiconductor substrate in a plasma chamber as set forth above is provided. In the method according to the present invention, a substrate is transferred into the plasma chamber and an exposed surface of the substrate is processed with a plasma. In a further preferred embodiment of the present invention, the method includes steps of: positioning the substrate on a substrate support in the reactor; introducing a process gas into the reactor; applying RF energy to the process gas to generate a plasma adjacent an exposed surface of the substrate; and etching or otherwise processing the exposed substrate surface with a plasma.